Electrolytic solution for cleaning metallic articles.



which permits iron,

UNITED STATES PATENT oF IoE.

ALFRED LEVY, or PARIS, FRANCE, Assieuo'r't'ro ALEXANDRE WALDBERG, or PARIS,

. FRANCE.

ELECTROLYTIC SOLUTION FOR; CLEANING METALLIC ARTICLES.

N 0 Drawing.

that when the operator does not require to use graphite, which is very expens1ve,-or ag glomerated carbon which disintegrates very rapidly, he generally uses an. iron anode which has been considered to be insoluble in such electrolyte; this insolubility however is not real, as the iron anode is finally attacked under the action of the current, and the electrolyte is polluted and imperfectiron deposits are produced with the result that the preparation of the articles is interfered with. The second difliculty is, that it is impossible to use such an electrolyte for cleaning soft metals or soldered metals, because,

the electrolyte in spite of all precautions, at-' tacks the white metals and the articles which are to be cleaned show the presence of a white film which becomes more and more disturbing in subsequent operations, when the quantity of the dissolved white metal is increased. Besides, the presence of white metal in the electrolyte causes the anode to be more quickly attacked with the-result that the electrolyte has to be thrown away and replaced by a new one which has again as quickly to be replaced in its turn.

The present invention has for its object to radically remedy the two above mentioned ditficulties.

For the purpose of meeting the first difiiculty Iuse in the electrolytic cleaning electrolyte instead of alkaline cyanid, prussiate of potassium (ferro-cyanid or ferri-cyanid) steel, nickel or the like or any alloy of these or similarmetals to be used as an anode. It would be even possible to use as anodes a metal which would be attacked by the electrolyte under the influence of the current or not, if the products of such attacks were or would become insoluble in such electrolyte, but I do not recommend the use of a metal which would be so attacked.

Specification of Letters Patent. Application filed December 4, 191,2.

Patented May 6, 1913. Serial No. 734,895.

This electrolyte can be used without inconvenience for the however of soldered metals or white metals. 7 To meet the second difiiculty which presents itself when cleaning soldered or. white metals, the above mentioned modification in the electrolyte would not be suflicient. But I obtain the desired result by adding to the electrolyte above described, a certain quantity of chalk; the simultaneous presence of a prussiate and of chalk (excluding any alkaline cyanid) will produce the desired result.

As a matter of fact the prussiate which does purpose of all metals, except not itself dissolve the soldered metal, nevertheless, does not prevent the dissolving of this solder by the alkaline body, which is the base of the electrolyte; and the passage of the current in such an electrolyte would lead to a white deposit. But the presence of chalk causes the precipitation of the white metal in the form of insoluble bodies, in proportion as it dissolves in the alkaline body it evidently would not be the same in the presence of an alkaline cyanid, which would dissolve the white metal in order to form a double cyanid, from which the chalk could not precipitate the white metal. The simultaneous employment of a prussiate and chalk (to the exclusion of any alkaline cyanid) is therefore'indispensable in order to obtain the desired result. With such an electrolytic cleaning bath, it will be necessary to stir the electrolyte from time to time so as to get the chalk into suspension again, and permit it toaccomplish its .Work during the course of the operation. When it is a question of cleaning articles made of a metal "which can be employed as the anode in such a bathfsuch as iron, for example, one could, of course, use these articles successively as anodes and cathodes, by reversing the direction of the current; and this would permit of the work being accomplished more rapidly. One'might even if one is using certain definite anodes, as stated above, usefully have recourse in certain cases to reversing the current. with an electrolytethusmodified, one can employ anodes otgraphite or of carbon, if one does not fear the objections attached to their use, and referred to above.

The quantity of chalk to be employed may be very variable and, in case of need, a fresh quantity may be added to the bath after it has already been in operation. By way of example I may state that a weight of chalk equal to one-tenth of the Weight of the alkaline body which is the base of the electrolyte will be sufficient, but I do not bind myself to these proportions.

The following is the formula of a bath which gives excellent results: Water 100 liters Ferro-cyanid of potassium 1 kilogram Caustic potash 10 kilograms Chalk 1 kilogram In the same Way I do not bind myself to tended to mean either the ferro or ferri cyanicl of potassium.

1. An electrolytic solution for cleaning metallic articles, comprising a prussiate of potash.

2. An electrolytic solution for cleaning metallic articles, comprising a prussiate of potash, with the addition of chalk, as and for the purpose set forth.

3. An electrolytic solution for cleaning Il'letdlllc articles, comprising a prussiate ot' potash, caustic soda and chalk, as and for the purpose set forth.

in Witness whereof I subscribe my signature in the presence of two Witnesses.

' ALFRED LEVY. Witnesses ALEXANDER LUMLEY,

LEONCE CAYnoN. 

